With the arrival of fall also comes the expectation of heavy rains and flooding. The swells of moisture can cause surface floods and flash floods, riverbanks that brim over, and sea surges spread across coastal cities. At best, it’s inconvenient, at worst, it turns tragic. In September alone two people died from severe flooding in Wisconsin, and in Cedar Rapids, Iowa, city officials are still warning more than 10,000 evacuees not to return home.

In fact, today flooding is so pervasive FEMA reports it as the most common natural disaster in the U.S. To alleviate impacts and improve recovery, Baton Rouge, La., and GIS mapping firm Esri partnered to launch a series of apps cities might consider to track flooding and inform residents during major weather-related events. Among these are a tracking app that offers near real-time mapping of flood zones, an app that locates open businesses and a “swipe map” that visualizes before-and-after images of inundated areas.

The catalyst for the inventions came in the wake of severe flooding on Aug. 11. National news outlets chronicled the devastation that claimed the lives of 13 residents, damaged 40,000 homes, put more than 8,000 people in shelters and had some 70,000 people requesting for government aid. While the media spotlight has moved elsewhere, Baton Rouge residents expect to be in the recovery and rebuilding mode for quite a while.

Warren Kron, GIS manager at the city’s Department of Information Services, said he remembered the scramble to help residents. The rains hit on a Friday and gained force Saturday and Sunday. This sent first responders, many with affected homes of their own, darting to answer a barrage of 911 calls. While they had a rough idea, authorities didn’t have exact information about the flood zones, what resources were available to help with the effort and the flood’s trajectories. This is where Kron and his team went to work.

“At the time, we didn’t have much data in our hands, so we took what we had, which were a few 911 calls that were all clustered in one area of the parish and we used that to fill in some sort of estimated inundation area,” Warren said. “What we found as we gathered more and more data — like search-and-rescue call data, 311 calls for service and analyzing the 100-year flood area — we realized that we grossly underestimated the inundated areas on the first pass. So as the week went on, we kept compiling data and came up with something that we were pretty confident about the following Friday.”

Warren and his fellow team members came up with a crowdsourced Web map that saw instant success. There was a boom in traffic with contributions sent in by both city staff reporting in the field and residents who were updating estimates. In the first 24 hours 20,000 people viewed the map, in three days this jumped to 30,000 unique users, and in the second week figures broke 80,000. Baton Rouge Director of Information Services Eric Romero said it was a welcome surprise.

“Initially it wasn't intended to be a collection mechanism, and to be honest, that's really our first foray into crowdsourcing, but once we put the map out there on Facebook, people started responding,” Romero said. “They give feedback like ‘Hey, my area just flooded, and the map doesn’t show this,’ or ‘Hey, my house didn't flood, please take me off the map.’”

Eventually this yielded a heightened accuracy into the number of flooded structures, which of those were residential, businesses or public facilities, and most importantly, the total number of people affected. Efficiency and effectiveness was drastically improved compared to past responses.

“I remember there were days [in previous natural disasters] at our [Emergency Operations Center], where we just had sheets after sheets after sheets of paper — and it's not just 8.5 x 11 — it was big, 30-x-30, 42-x-42 sheets of paper that filled up rooms. We just had to keep printing maps,” Romero said. “Now, with Esri ArcGIS Online, we're still entering in that data, but as soon as we enter it in, it's immediately available.”

Esri, which has developed emergency management tools over the years for all varieties of incidents, has a Disaster Response Program that aided Baton Rouge and the state in their efforts to combat the flood. In addition to the swipe map, the business map and a precipitation map, the primary service provided was the ability to collect, combine and interpret the data.

Chris McIntosh, Esri’s emergency management industry manager, said the company's goal is to serve the public with actionable intelligence.

“Through the Disaster Response Program, we assisted Baton Rouge in bringing all this information together and creating decision products that are designed for decision-makers at the emergency operations centers,” he said. “One of the key things they wanted help with was answering questions like 'What's going on with a certain business in the community? What's open? What's available?' And the best way to find that information out is through crowdsourcing.”